Fix C++ reference to C++ reference coercion

with some improvements to previously committed test case

DefNode refactoring and initial closure function call inlining

It seems that a templated class method (Foo[T].set_bar)
which should accept a reference to another templated type (Bar[T] &)
can't actually do so and throws an error.

Support for dynamic default arguments, fix #674

Buffer format arrays, strings and alignment on first member

fixes missing sentinel in Generator member list